As part of its mounting United States rollout of content-enhanced and copy-protected CDs, Sony BMG is testing technology that bars consumers from making additional copies of burned CD-R discs.

Since March the company has released at least 10 commercial titles - more than 1 million discs in total, featuring technology from UK anti-piracy specialist First4Internet that allows consumers to make limited copies of protected discs, but blocks users from making copies of the copies.